l^tJLP OF TEETH 



204 



PYRROL COMPOUNDS 



plicable. Wellings, A. W., Practical 

 Microscopy of Teeth and Associated 

 Parts. London: John Bale, Sons & 

 Curnow, Ltd. 1938, 281 pp. gives many 

 of them. See Teeth, Innervation. 



Purines. Silver methods for histochemical 

 detection are according to Lison (p. 

 185) absolutely useless. 



Psittacosis, method for staining elementary 

 bodies (Hornus, G. J. P., Ann. Inst. 

 Pasteur, 1940, 64, 97-116). See other 

 kinds of Elementary Bodies. 



Purkinje Cells of heart. Distend entire 

 heart by injecting fixative through 4 

 cannulas, in aorta, in pulmonary artery, 

 in superior vena cava, in one pulmonary 

 vein and ligating other vessels. Fix 

 in Zenker's or Bouin's fluid. Sino- 

 auricular node is at junction of superior 

 vena cava and right auricle. Cut blocks 

 perpendicular to the node. Color paraf- 

 fin sections with Masson's tri chrome 

 stain or with hematoxylin and eosin for 

 transitions between Purkinje and car- 

 diac muscle cells. The sharpest differ- 

 ential stain for the former is Best's 

 carmine stain for glycogen (Taussig, 

 H. B., J. Tech. Methods, 1934, 13, 85- 

 87). 



Purkinje Fibers. In excising the specimen 

 the presence of Purkinje fibers is lo- 

 calized by the dimpling in a cross section 

 because in the fresh state the Purkinje 

 fibers contract more than the cardiac 

 fibers (Todd, T. W. in Cowdry's Special 

 Cytology, 1932, 2, 1179). Todd recom- 

 mends for general purposes Bouin's 

 fixative and Mallory's stain. Safranin 

 light green is good for the intercalated 

 discs (Jordan, H. E., and Banks, J. B., 

 Am. J. Anat., 1917, 22, 285-338). Tech- 

 niques for bringing out the Purkinje 

 system particularly of mammalian ven- 

 tricles are described by Abramson, 

 D. I. and Margolin, S., J. Anat., 1935- 

 36, 70, 250-259. 



Purpurin (CI, 1037) — alizarin No. 6, alizarin 

 purpurin — An acid anthraquinon dye. 

 The bright red color of madder-stained 

 bones is due to purpurin carboxylic acid 

 (Richter, D., Biochem. J., 1937, 31, 

 591-595). 



Pycnosis (G. pyknos, dense) When the sub- 

 stance of a cell, as seen in stained sec- 

 tions is unusually dense it is sometimes 

 said to be pycnotic. The increase in 

 density is usually accompanied by a 

 decrease in size of cytoplasm and/or 

 nucleus and the nucleus may be hyper- 

 chromatic, that is have an increased 

 affinity for stains like hematoxylin and 

 methylene blue. Sometimes pycnotic 

 cells occur singly surrounded by otliers 

 not in the same condition but they may 

 be present in group. Those in the cen- 

 tral nervous system have been called 

 chromophile cells (Cowdry, E. V., 



Contrib. to Embry., Carnegie Inst., 

 1917, 11, 29-41). Information is needed 

 on the cause or causes of pycnosis and 

 on the fate of cells in this condition. 



Pyoktanin Yellow, see Auramin. 



Pyoktaninum Aureum, see Auramin. 



Pyoktaninum Coeruleum, see Methyl Vio- 

 let. 



Pyronin. There are 2 pyronins : B (CI, 

 741) and Y (CI, 739) also known as G. 

 Conn (p. 140) describes them as 

 closely related to diphenyl methanes 

 since they have one carbon atom at- 

 tached to 2 benzene rings and exhibit 

 similar tendency to quinone structure. 

 Their formula also resembles that of 

 oxazins except that nitrogen of central 

 ring is replaced by CH radical. Pyro- 

 nin B is tetra-ethyl diamino xanthene 

 and Y is the tetra -methyl compound. 

 Conn (McClung p. 599) advises Y with 

 methyl green in Pappenheim's stain, 

 for the granules of mast cells and the 

 gonococcus in smears of pus. B is satis- 

 factory for most purposes. Only re- 

 cently has the distinction been made 

 so that most formulae call simply for 

 pyronin. American pyronins are now 

 more concentrated than those imported 

 before 1914. Conn says that allowance 

 should be made for this difference in the 

 proportions of pyronin and methyl 

 green. 



Pyronin G is the best supravital stain 

 for the duct system of the pancreas 

 (Bensley,_ R. R., 1911, 12, 297-388). 

 It is applied by Perfusion a solution of 

 1:1000 in 0.85% aq. NaCl being used 

 until the pancreas takes a light rose 

 color. Small pieces are then mounted 

 in salt solution and examined. The 

 ducts from the main ones to the centro- 

 acinous cells are sharply stained in red 

 against an almost colorless background. 

 The ducts may be similarly stained by 

 methylene blue in a concentration of 

 1:10,000. To obtain a beautiful contrast 

 coloration Bensley injects with a salt 

 solution containing 1:100 pyronin and 

 1:15,000 janus green. This stains the 

 ducts red and the islets bluish green. 

 The combination of 1 : 1000 pyronin and 

 1:15,000 neutral red also demonstrates 

 ducts and islets but without an equally 

 distinct color contrast. The pyronin 

 method for ducts is one of the most use- 

 ful techniques both for investigation and 

 for class room demonstration. 



Pyrosin B, see Erythrosin, bluish. 



Pyroxylin (collodion cotton, colloxylin, 

 soluble gun cotton, xyloidin, cellodion 

 wood). It is chiefly cellulose tetra- 

 nitrite. Mainly used in manufacture of 

 Collodions, Celloidin, Paraloidin, Pho- 

 toxylin, etc. 



Pyrrol Compounds, see Nitro Reaction, 

 Nitrosamino Reaction. 



